To prepare a releasable sheet or a pressure-sensitive adhesive tape which are stabilized in the performance such as a desired releasability, coefficient of friction, writing properties, and printability using a heat transfer system.

A release agent composition is a blend of a polydimethylsiloxane with a polymeric resin, and a release sheet is obtained by coating the release agent composition on at least one side of a base material to form a release agent layer having an organic Si content at a depth of 5 nm in the surface layer (measured by electron spectroscopy for chemical analysis (ESCA)), of 5-30 atomic %. The polymeric resin is a cellulose derivative, a thermoplastic resin and/or a thermoplastic elastomer, and the release sheet is heat transfer- printable. A pressure-sensitive adhesive tape is provided with a pressure-sensitive adhesive layer on the opposite side of the release agent layer of the release sheet.